LXR linux/include/linux/sysctl.h

   1/*
   2 * sysctl.h: General linux system control interface
   3 *
   4 * Begun 24 March 1995, Stephen Tweedie
   5 *
   6 ****************************************************************
   7 ****************************************************************
   8 **
   9 **  WARNING:
  10 **  The values in this file are exported to user space via 
  11 **  the sysctl() binary interface.  Do *NOT* change the
  12 **  numbering of any existing values here, and do not change
  13 **  any numbers within any one set of values.  If you have to
  14 **  redefine an existing interface, use a new number for it.
  15 **  The kernel will then return -ENOTDIR to any application using
  16 **  the old binary interface.
  17 **
  18 ****************************************************************
  19 ****************************************************************
  20 */
  21#ifndef _LINUX_SYSCTL_H
  22#define _LINUX_SYSCTL_H
  23
  24#include <linux/list.h>
  25#include <linux/rcupdate.h>
  26#include <linux/wait.h>
  27#include <linux/rbtree.h>
  28#include <uapi/linux/sysctl.h>
  29
  30/* For the /proc/sys support */
  31struct ctl_table;
  32struct nsproxy;
  33struct ctl_table_root;
  34struct ctl_table_header;
  35struct ctl_dir;
  36
  37typedef int proc_handler (struct ctl_table *ctl, int write,
  38                          void __user *buffer, size_t *lenp, loff_t *ppos);
  39
  40extern int proc_dostring(struct ctl_table *, int,
  41                         void __user *, size_t *, loff_t *);
  42extern int proc_dointvec(struct ctl_table *, int,
  43                         void __user *, size_t *, loff_t *);
  44extern int proc_dointvec_minmax(struct ctl_table *, int,
  45                                void __user *, size_t *, loff_t *);
  46extern int proc_dointvec_jiffies(struct ctl_table *, int,
  47                                 void __user *, size_t *, loff_t *);
  48extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
  49                                        void __user *, size_t *, loff_t *);
  50extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
  51                                    void __user *, size_t *, loff_t *);
  52extern int proc_doulongvec_minmax(struct ctl_table *, int,
  53                                  void __user *, size_t *, loff_t *);
  54extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
  55                                      void __user *, size_t *, loff_t *);
  56extern int proc_do_large_bitmap(struct ctl_table *, int,
  57                                void __user *, size_t *, loff_t *);
  58
  59/*
  60 * Register a set of sysctl names by calling register_sysctl_table
  61 * with an initialised array of struct ctl_table's.  An entry with 
  62 * NULL procname terminates the table.  table->de will be
  63 * set up by the registration and need not be initialised in advance.
  64 *
  65 * sysctl names can be mirrored automatically under /proc/sys.  The
  66 * procname supplied controls /proc naming.
  67 *
  68 * The table's mode will be honoured both for sys_sysctl(2) and
  69 * proc-fs access.
  70 *
  71 * Leaf nodes in the sysctl tree will be represented by a single file
  72 * under /proc; non-leaf nodes will be represented by directories.  A
  73 * null procname disables /proc mirroring at this node.
  74 *
  75 * sysctl(2) can automatically manage read and write requests through
  76 * the sysctl table.  The data and maxlen fields of the ctl_table
  77 * struct enable minimal validation of the values being written to be
  78 * performed, and the mode field allows minimal authentication.
  79 * 
  80 * There must be a proc_handler routine for any terminal nodes
  81 * mirrored under /proc/sys (non-terminals are handled by a built-in
  82 * directory handler).  Several default handlers are available to
  83 * cover common cases.
  84 */
  85
  86/* Support for userspace poll() to watch for changes */
  87struct ctl_table_poll {
  88        atomic_t event;
  89        wait_queue_head_t wait;
  90};
  91
  92static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
  93{
  94        return (void *)(unsigned long)atomic_read(&poll->event);
  95}
  96
  97#define __CTL_TABLE_POLL_INITIALIZER(name) {                            \
  98        .event = ATOMIC_INIT(0),                                        \
  99        .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
 100
 101#define DEFINE_CTL_TABLE_POLL(name)                                     \
 102        struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
 103
 104/* A sysctl table is an array of struct ctl_table: */
 105struct ctl_table 
 106{
 107        const char *procname;           /* Text ID for /proc/sys, or zero */
 108        void *data;
 109        int maxlen;
 110        umode_t mode;
 111        struct ctl_table *child;        /* Deprecated */
 112        proc_handler *proc_handler;     /* Callback for text formatting */
 113        struct ctl_table_poll *poll;
 114        void *extra1;
 115        void *extra2;
 116};
 117
 118struct ctl_node {
 119        struct rb_node node;
 120        struct ctl_table_header *header;
 121};
 122
 123/* struct ctl_table_header is used to maintain dynamic lists of
 124   struct ctl_table trees. */
 125struct ctl_table_header
 126{
 127        union {
 128                struct {
 129                        struct ctl_table *ctl_table;
 130                        int used;
 131                        int count;
 132                        int nreg;
 133                };
 134                struct rcu_head rcu;
 135        };
 136        struct completion *unregistering;
 137        struct ctl_table *ctl_table_arg;
 138        struct ctl_table_root *root;
 139        struct ctl_table_set *set;
 140        struct ctl_dir *parent;
 141        struct ctl_node *node;
 142};
 143
 144struct ctl_dir {
 145        /* Header must be at the start of ctl_dir */
 146        struct ctl_table_header header;
 147        struct rb_root root;
 148};
 149
 150struct ctl_table_set {
 151        int (*is_seen)(struct ctl_table_set *);
 152        struct ctl_dir dir;
 153};
 154
 155struct ctl_table_root {
 156        struct ctl_table_set default_set;
 157        struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
 158                                           struct nsproxy *namespaces);
 159        int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
 160};
 161
 162/* struct ctl_path describes where in the hierarchy a table is added */
 163struct ctl_path {
 164        const char *procname;
 165};
 166
 167#ifdef CONFIG_SYSCTL
 168
 169void proc_sys_poll_notify(struct ctl_table_poll *poll);
 170
 171extern void setup_sysctl_set(struct ctl_table_set *p,
 172        struct ctl_table_root *root,
 173        int (*is_seen)(struct ctl_table_set *));
 174extern void retire_sysctl_set(struct ctl_table_set *set);
 175
 176void register_sysctl_root(struct ctl_table_root *root);
 177struct ctl_table_header *__register_sysctl_table(
 178        struct ctl_table_set *set,
 179        const char *path, struct ctl_table *table);
 180struct ctl_table_header *__register_sysctl_paths(
 181        struct ctl_table_set *set,
 182        const struct ctl_path *path, struct ctl_table *table);
 183struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
 184struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
 185struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
 186                                                struct ctl_table *table);
 187
 188void unregister_sysctl_table(struct ctl_table_header * table);
 189
 190extern int sysctl_init(void);
 191
 192extern struct ctl_table sysctl_mount_point[];
 193
 194#else /* CONFIG_SYSCTL */
 195static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
 196{
 197        return NULL;
 198}
 199
 200static inline struct ctl_table_header *register_sysctl_paths(
 201                        const struct ctl_path *path, struct ctl_table *table)
 202{
 203        return NULL;
 204}
 205
 206static inline void unregister_sysctl_table(struct ctl_table_header * table)
 207{
 208}
 209
 210static inline void setup_sysctl_set(struct ctl_table_set *p,
 211        struct ctl_table_root *root,
 212        int (*is_seen)(struct ctl_table_set *))
 213{
 214}
 215
 216#endif /* CONFIG_SYSCTL */
 217
 218int sysctl_max_threads(struct ctl_table *table, int write,
 219                       void __user *buffer, size_t *lenp, loff_t *ppos);
 220
 221#endif /* _LINUX_SYSCTL_H */
 222